MEASURING THE TEMPERATURE OF A HEATING ELEMENT OF AN ELECTRONIC CIGARETTE

Abstract

A vaporizer for vaporizing a liquid comprises a heating element for receiving electrical power and for delivering thermal power to a liquid to be vaporized and a temperature sensor for sensing the temperature of the heating element. The temperature sensor and the heating element are directly mechanically connected and thermally coupled.

Claims

1. A vaporizer for vaporizing a liquid, the vaporizer comprising: a heating element to receive electrical power and to deliver thermal power to a liquid to be vaporized; and a temperature sensor to sense the temperature of the heating element, the temperature sensor and the heating element being directly mechanically connected and thermally coupled.

2. The vaporizer according to claim 1, wherein the temperature sensor and the heating element are electrically conductively connected.

3. The vaporizer according to claim 1, wherein the temperature sensor comprises a sensing junction of a thermocouple.

4. The vaporizer according to claim 1, wherein the temperature sensor and the heating element are directly mechanically connected and thermally coupled to each other by a welded joint.

5. The vaporizer according to claim 1, wherein the heating element is formed as a mesh or grid, wherein the heating element comprises a full-surface region without holes, meshes or other recesses, and wherein the temperature sensor is directly mechanically connected and thermally coupled to the full-surface region of the heating element.

6. The vaporizer according to claim 1, wherein a plurality of temperature sensors are spatially distanced from one another and are each directly mechanically connected and thermally coupled to the heating element.

7. A power source module comprising: an interface to mechanically and electrically connect the power source module to a corresponding interface at a vaporizer comprising a heating element to receive electrical power and to deliver thermal power to a liquid to be vaporized and a temperature sensor to sense the temperature of the heating element, the temperature sensor and the heating element being directly mechanically connected and thermally coupled; a temperature measuring circuit to detect a temperature signal of the temperature sensor; and a power source coupled to the temperature measuring circuit to provide electrical power to the heating element of the vaporizer in response to the temperature signal detected by the temperature measuring circuit.

8. The power source module according to claim 7, wherein the interface of the power source module includes electrical power contacts to transmit electrical power via corresponding electrical power contacts of the vaporizer to the heating element of the vaporizer and electrical signal contacts to receive a temperature signal from the temperature sensor of the vaporizer via the corresponding signal contacts of the vaporizer.

9. The power source module according to claim 8, wherein the temperature measuring circuit is configured to detect a difference of a thermoelectric voltage at a thermocouple's sensing junction and a thermoelectric voltage at a reference junction, the reference junction being formed by the signal contacts.

10. The power source module according to claim 9, further comprising a further temperature sensor to sense the temperature of the reference junction, wherein the further temperature sensor is arranged between the signal contacts of the power source module.

11. The power source module according to claim 7, wherein the temperature measuring circuit comprises a high impedance linear or non-linear differential amplifier.

12. The power source module according to claim 7, wherein the temperature measuring circuit is configured to detect a temperature signal of a temperature sensor electrically conductively connected to the heating element of the vaporizer.

13. The power source module according to claim 7, wherein the temperature measuring circuit comprises its own power source galvanically insulated from the power contacts of the power source module.

14. The power source module according to claim 7, wherein the temperature measuring circuit comprises an analog-to-digital converter and an integer computation of the digital output signal provided by the analog-to-digital converter.

15. The power source module according to claim 7, wherein the temperature measuring circuit and a power control coupled to the temperature measuring circuit are of analog design.

16. The power source module according to claim 7, wherein the interface of the power source module comprises a decoder to decode a target temperature encoded by the interface of the vaporizer module.

17. The power source module according to claim 16, wherein the signal contacts of the power source module are positioned corresponding to predetermined optional positions of the signal contacts of the vaporizer, the target temperature is encoded in the positions of the signal contacts at the interface of the vaporizer, the decoder is configured to decode the target temperature on the basis of the signal contacts of the power source module which are contacted by the signal contacts of the vaporizer.

18. The power source module according to claim 7, wherein two or more signal contacts of the power source module are positioned on a circle concentric to at least one power contact of the power source module.

19. An electric smoking or vaporizing system comprising: a vaporizer comprising a heating element to receive electrical power and to deliver thermal power to a liquid to be vaporized and a temperature sensor to sense the temperature of the heating element; and a power source module comprising: an interface to mechanically and electrically connect the power source module to a corresponding interface at the vaporizer; a temperature measuring circuit to detect a temperature signal of a temperature sensor directly mechanically connected and thermally coupled to the heating element of the vaporizer; and a power source coupled to the temperature measuring circuit to provide electrical power to the heating element of the vaporizer in response to the temperature signal detected by the temperature measuring circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0069] FIG. 1 shows a schematic representation of an electronic cigarette;

[0070] FIG. 2 shows another schematic representation of the electronic cigarette shown in FIG. 2;

[0071] FIG. 3 shows a schematic representation of an alternative embodiment of a heating element of the electronic cigarette shown in FIGS. 1 and 2; and

[0072] FIG. 4 shows a schematic representation of an interface of a battery carrier of the electronic cigarette shown in FIGS. 1 and 2.

DETAILED DESCRIPTION

[0073] FIG. 1 shows a schematic representation of an electronic cigarette 10 as an example of an electric smoking or vaporizing system for generation of an inhalable aerosol from a liquid. The liquid and thus also the aerosol may contain nicotine and/or flavor or release them during vaporization. The electronic cigarette 10 comprises a battery carrier 20 and a vaporizer 80 shown spaced apart in FIG. 1 which can be mechanically and electrically connected to each other as described with reference to FIGS. 2. Housings of the battery carrier 20 and the vaporizer 80 are shown in a sectional view to make members and components inside the housing visible.

[0074] The battery carrier 20 is an example of a power source module for delivering electrical power to the vaporizer 80.

[0075] The battery carrier 20 comprises a user interface 22 for receiving a user input. In the example shown, the user interface 22 is formed by a simple electrical push button. By actuating the user interface, namely pressing the push button, a user can request the generation of aerosol.

[0076] The battery carrier 20 further comprises a first power source 26 and a second power source 28. The first power source 26 in particular comprises one or more secondary cells (also referred to as rechargeable battery) and is provided and configured for providing electrical power to the vaporizer 80. As an alternative, the first power source 26 can comprise one or more primary cells, fuel cells or other sources of electrical power.

[0077] In the example shown, the second power source 28 is provided and configured only for providing electrical power for the battery carrier itself and comprises one or more primary cells, for example. As an alternative, the second power source 28 may comprise one or more secondary cells or other power sources or one or more capacitors. As an alternative, the second power source 28 can comprise a circuit receiving electrical power from the first power source 26 and providing electrical power with a predetermined voltage substantially or entirely independent from the voltage of the first power source 26. In any case, the power output of the second power source 28 is galvanically isolated or high impedance insulated from the first power source 26.

[0078] The battery carrier 20 further comprises a temperature detecting and controlling device 30, in particular formed by a microcontroller or comprising a microcontroller. The temperature detecting and controlling device 30 comprises a first signal input 32 coupled to the user interface 22 for receiving a request signal from the latter. Further, the temperature detecting and controlling device 30 comprises a (high impedance) second signal input 34 for receiving an electrical voltage signal. Furthermore, the temperature detecting and controlling device 30 comprises a third signal input 36 connected to a temperature sensor 44, for receiving a temperature signal. Further, the temperature detection and control device 30 comprises a control signal output 38 for providing a control signal in response to the request signal, the voltage signal and the temperature signal. Further, the temperature detection and control device 30 comprises a power input 42 connected to the second power source 28, for receiving electrical power.

[0079] The battery carrier 20 further comprises a power control 50. The power control 50 comprises a control signal input 52 coupled to the control signal output 38 of the temperature detection and control device 30, for receiving the control signal provided by the temperature detection and control device 30. Further, the power control 50 comprises a power input 56 connected to the first power source 26, for receiving electrical power provided by the first power source 26. Further, the power control 50 comprises a power output 58 for providing electrical power controlled by the control signal received at the control signal input 52 from the temperature detection and control device 30.

[0080] As an example, the power control 50 is depicted as a relay. For example, the power control 50 comprises a semiconductor relay for connecting the control output 58 to the control input 56. As an alternative, the power control 50 is provided and configured not only for switching provided power on and off, but for controlling power delivered in a plurality or in many steps or continuously between a predetermined minimum value (in particular zero) and a predetermined maximum value.

[0081] The control signal input 52 of the power control 50 on the one hand side and the power inputs and outputs 56, 58 of the power control 50 on the other hand are high-impedance insulated or galvanically isolated, for example by means of an optocoupler. As an alternative, the control signal output 38 of the temperature detecting and controlling device 30 on the one hand side and the second signal input 34 of the temperature detecting and controlling device 30 on the other hand are high-impedance insulated or galvanically isolated, for example by means of an optocoupler. The resulting high impedance insulation or galvanical isolation of the second signal input 34 from the power inputs and outputs 56, 58 of the power control 50 facilitates detection of a voltage provided at the second signal input 34 largely or completely independent of electrical voltages between the second signal input 34 and the power inputs and outputs 56, 58 of the power control 50.

[0082] The battery carrier 20 further comprises an interface 60 for mechanical and electrical connection to a corresponding interface 70 of a vaporizer 80 of the electronic cigarette 10. The mechanical connection can be, for example, one or more screw threads, a swivel connection (often also referred to as a bayonet connection), a snap-in connection or magnets.

[0083] The interface 60 of the battery carrier 20 comprises a first signal contact 62 and a second signal contact 64 connected to the second signal input 34 and a first power contact 66 and a second power contact 68 connected to the power output 58 of the power control 50.

[0084] The interface 70 of the vaporizer 80 comprises a first signal contact 72 and a second signal contact 74 corresponding to the first signal contact 62 and the second signal contact 64, respectively, of the interface 60 of the battery carrier 20. The first signal contact 72 of the interface 70 of the vaporizer 80 is connected to the second contact 74 of the interface 70 of the vaporizer 80 by means of a first conductor 92 from a first material and a second conductor 94 from a second material different from the first material. Due to the Seebeck effect, at each junction between two different materials, a thermoelectric voltage depending on the temperature of the junction accrues. The direct connection of both conductors 92, 94 is referred to as sensing junction 86 often also shortened as thermocouple.

[0085] The interface 70 of the vaporizer 80 further comprises a first power contact 76 and a second power contact 78 corresponding to the first power contact 66 and the second power contact 68 of the interface 60 of the battery carrier. The power contacts 76, 78 of the interface 70 of the vaporizer 80 are connected by a heating element 82 for receiving electrical power and providing thermal power. In the example shown, the heating element 82 is a helix made from resistance wire.

[0086] FIG. 2 shows a further schematic representation of the battery carrier 20 and the vaporizer 80. The form of representation, in particular the position of the drawing plane, corresponds to that of FIG. 1. The representation in FIG. 2 differs from the representation in FIG. 1 in that the battery carrier 20 and the vaporizer 80 are mechanically connected to each other in a manner not shown, such that the first signal contact of the interface 60 of the battery carrier 20 touches the first signal contact 72 of the interface 70 of the vaporizer 80, the second signal contact 64 of the interface 60 of the battery carrier 20 touches the second signal contact 74 of the interface 70 of the vaporizer 80, the first power contact 66 of the interface 60 of the battery carrier 20 touches the first power contact 76 of the interface 70 of the vaporizer 80 and the second power contact 68 of the interface 60 of the battery carrier 20 touches the second power contact 78 of the interface 70 of the vaporizer 80.

[0087] The signal contacts 62, 64 of the interface 60 of the battery carrier 20 and the signal contacts 72, 74 of the interface 70 of the vaporizer 80 form a reference junction 88 the temperature of which is detected by the temperature sensor 44. For this purpose, the signal contacts 62, 64, 72, 74 are arranged within as small a volume of space as possible and are thermally coupled to one another as well as possible. Furthermore, the temperature sensor 44 is located as close as possible to the signal contacts 62, 64, 72, 74, in particular between them or in their immediate vicinity.

[0088] If and in so far as within the battery carrier 27 the two conductors between the signal contacts 72, 74 and the second signal input 34 of the temperature detection and control device 30 can be formed of the same material—for example copper—a difference between the thermoelectric voltages at the sensing junction 86 and at the reference junction 88 is applied to the high-impedance second signal input 34 of the temperature detection and control device 30. The temperature detection and control device 30 calculates the thermoelectric voltage accruing at the reference junction 88 from the temperature of the reference junction 88 detected by means of the temperature sensor 44, calculates the thermoelectric voltage accruing at the sensing junction 86 from the thermoelectric voltage at the reference junction 88 and the voltage at the second signal input 34 detected by the temperature detection and control device 30, and calculates from the thermoelectric voltage accruing at the sensing junction 86 the temperature of the sensing junction 86.

[0089] The sensing junction 86 is directly mechanically and thus also thermally connected to the heating element 82 by means of spot weld. Since the sensing junction 86 itself, as a small-volume connection of two thin conductors 92, 94, has low thermal inertia and is directly thermally coupled to the heating element 82, the arrangement shown permits an extremely low-delay, i.e. fast and at the same time precise, detection of the temperature of the heating element 82.

[0090] The sensing junction 86 is located at the center of the heating element 82, where the highest temperature of the heating element 82 can be expected. This arrangement facilitates a reliable detection of the maximum temperature of the heating element 82.

[0091] When the temperature detection and control device receives at its first signal input 32 a request signal caused by a user at the user interface 22, the temperature detection and control device 30 at its control signal output 38 provides a control signal controlling the power control 50 such that the heating element is heated to a predetermined maximum temperature and then maintained at that maximum temperature.

[0092] As mentioned above and shown in FIGS. 1 and 2, the second signal input 34 of the temperature detection and control device 30 can be galvanically isolated from the power inputs and outputs 56, 58 of the power control 50 and thus also from the first power source 26 and, with regard to the connection via the power control 50, from the heating element. Alternatively, and contrary to the illustration in FIG. 1, there may be a high impedance connection (particularly at least 10 kΩ or at least 100 kΩ) between the power input 42 of the temperature detection and control device 30 and the power input 56 of the power control and/or between the control signal output 38 of the temperature detection and control device 30 and the control signal input 52 of the power control. This may allow for omission of optocouplers and/or omission of primary or secondary cells or the like in the second power source 28 for the temperature detection and control device 30. Instead, the second power source 28 may receive electrical power from the first power source 26.

[0093] Both galvanic isolation and a high-impedance connection can facilitate accurate detection of small differences (typically in the order of one mV) of the small thermoelectric voltages at the sensing junction 86 and the reference junction 88 even if the sensing junction 86 is galvanically connected to the heating element 82 by the spot weld.

[0094] However, an advantage of the configuration shown in FIGS. 1 and 2 with a separate power source 28 for the temperature detection and control device 30 may be that retroactive effects from fluctuations in the output voltage of the first power source 26 on the temperature detection and control device 30 can be avoided even without special circuitry.

[0095] FIG. 3 shows a schematic representation of an alternative embodiment of a heating element 82. The heating element 82 shown in FIG. 3 is configured as a flat rectangular mesh or grid with numerous recesses or openings or holes. In the center of the heating element 82 a full-surface region 84 without recesses or openings or holes is provided. The sensing junction 86 is located at the full-surface region 84 to which it can be connected in a particularly reliable and permanent manner, for example by a spot weld.

[0096] Unlike the illustration in FIG. 3, the first conductor 92 and the second conductor 94 can be connected to each other at multiple locations, i.e. at multiple sensing junctions 86. In this case, the multiple sensing junctions 86 are in particular arranged along an equipotential line, i.e. a line orthogonal to the current flow and current density distribution in the heating element 82. In this way it can be avoided that a part of the current flowing through the heating element 82 for ohmic heating flows through the conductors 92, 94.

[0097] However, it is advantageous for the conductors 92, 94 to be conductively connected to the heating element 82 only at the sensing junction 86 or the sensing junctions 86. For example, if only one of the conductors 92, 94 is electrically conductively connected to the heating element 82 at a further location that is not on an equipotential line with the sensing junction 86 or the sensing junctions 86, part of the current provided for ohmic heating of the heating element 82 flows through the conductor 92, 94 and, due to its resistance, generates a voltage that may distort the detection of the thermoelectric voltage and/or destroy the temperature detection and control device 30.

[0098] Many electrically insulating materials, in particular mechanically flexible and at the same time electrically insulating materials, can emit harmful substances when heated. Therefore, the conductors 92, 94 are in particular not electrically insulated. In this case, avoidance of electrically conductive contact between the heating element 82 and a conductor 92, 94 away from the sensing junction 86 or sensing junctions 86 can be ensured by the spatial arrangement and the shape of the conductors 92, 94.

[0099] FIG. 4 shows a schematic representation of the interface 60 of the battery carrier 20. The drawing plane of FIG. 4 is orthogonal to the drawing planes of FIGS. 1 and 2.

[0100] In the example shown, the interface 60 is circular. The power contacts 66, 68 are arranged concentric, wherein power contact 66 is located in the center and the other power contact is circular in shape and, for example, located at the rim of the housing of the battery carrier 20. Furthermore, one of the power contacts 66, 68 can be configured as a thread for a detachable mechanical connection of the battery carrier 20 to the vaporizer.

[0101] The interface 60 of the battery carrier 20 comprises a first signal contact 62 and three second signal contacts 64. In the example shown, all signal contacts 62, 64 are located on a circular circumference concentric with the power contacts 66, 68. The three second signal contacts 64 are provided for alternative contacting by a single second signal contact 74 of the interface 70 of the vaporizer 80 (cf. FIGS. 1, 2). The arrangement of the second signal contact 74 of the interface 70 of the vaporizer 80 corresponding to one of the second signal contacts 64 of the interface 60 of the battery carrier 20 encodes one of three alternatively provided target or maximum temperatures. The temperature detection and control device 30 decodes the intended target or maximum temperature of the vaporizer by detecting which of the second signal contacts 64 is contacted by the second signal contact 74 of the interface 70 of the vaporizer 80.

[0102] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.